Linux Java OpenMPI 安装

下载jdk8:http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

解压jdk:

tar -zxvf /Dowloads/jdk-8u161-linux-x64.tar.gz

下载openMPI：https://www.open-mpi.org/software/ompi/v3.0/

解压OpenMPI：

tar -zxvf /Dowloads/openmpi-3.0.0.tar.gz

配置包含Java的Makefile，编译：

./configure --prefix=/opt/openmpi --enable-mpi-java ##不加prefix可能找不到mpi.jar

make

sudo make install

配置环境变量（如 .bashrc）

export JAVA_HOME=/root/Downloads/jdk1.8.0_161
export JRE_HOME=${JAVA_HOME}/jre
export MPI_HOME=/opt/openmpi
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib:${MPI_HOME}/lib
export PATH=${JAVA_HOME}/bin:${MPI_HOME}/bin:$PATH

检查是否正常运行

import mpi.*;

class ComputePi {

    public static void main(String args[]) throws MPIException {

        MPI.Init(args);

        int rank = MPI.COMM_WORLD.getRank(),
            size = MPI.COMM_WORLD.getSize(),
            nint = 100; // Intervals.
        double h = 1.0/(double)nint, sum = 0.0;

        for(int i=rank+1; i<=nint; i+=size) {
            double x = h * ((double)i - 0.5);
            sum += (4.0 / (1.0 + x * x));
        }

        double sBuf[] = { h * sum },
               rBuf[] = new double[1];

        MPI.COMM_WORLD.reduce(sBuf, rBuf, 1, MPI.DOUBLE, MPI.SUM, 0);

        if(rank == 0) System.out.println("PI: " + rBuf[0]);
        MPI.Finalize();
    }
}

在当前路径下建立hosts文件（单机）

localhost    slots=4 ##表示使用本机的4个进程

编译并运行代码

mpijavac ComputePi.java
mpiexec --hostfile hosts -np 4 --allow-run-as-root java ComputePi

显示结果：

PI: 3.141600986923125

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